<?php

namespace StudyBuddy;

class Markdownbase {
    const MARKDOWN_EMPTY_ELEMENT_SUFFIX = " />";

    const MARKDOWN_TAB_WIDTH = 4;

    const MARKDOWN_FN_LINK_TITLE = '';

    const MARKDOWN_FN_BACKLINK_TITLE= "";

    # Optional class attribute for footnote links and backlinks.
    const MARKDOWN_FN_LINK_CLASS= "";
    const MARKDOWN_FN_BACKLINK_CLASS= "";

    # Regex to match balanced [brackets].
    # Needed to insert a maximum bracked depth while converting to PHP.

    protected $nested_brackets_depth = 6;
    protected $nested_brackets_re;
    protected $nested_url_parenthesis_depth = 4;
    protected $nested_url_parenthesis_re;

    # Table of hash values for escaped characters:
    protected $escape_chars = '\`*_{}[]()>#+-.!';
    protected $escape_chars_re;

    # Change to ">" for HTML output.
    protected $empty_element_suffix = self::MARKDOWN_EMPTY_ELEMENT_SUFFIX;
    protected $tab_width = self::MARKDOWN_TAB_WIDTH;

    # Change to `true` to disallow markup or entities.
    protected $no_markup = false;
    protected $no_entities = false;

    # Predefined urls and titles for reference links and images.
    protected $predef_urls = array();
    protected $predef_titles = array();


    # Internal hashes used during transformation.
    protected $urls = array();
    protected $titles = array();
    protected $html_hashes = array();

    /**
     * Status flag to avoid invalid nesting.
     *
     * @var bool
     */
    protected $in_anchor = false;

    /**
     * String length protected function for detab. `_initDetab`
     * will create a protected function to
     * hanlde UTF-8 if the default protected function does not exist.
     *
     * @var string
     */
    protected $utf8_strlen = 'mb_strlen';

    /**
     * Strip link definitions, store in hashes.
     *
     * @var array
     */
    protected $document_gamut = array(
        "stripLinkDefinitions" => 20,
        "runBasicBlockGamut" => 30,
    );

    /**
     * These are all the transformations that form block-level
     * tags like paragraphs, headers, and list items.
     *
     * @var array
     */
    protected $block_gamut = array(
        "doHeaders" => 10,
        "doHorizontalRules" => 20,
        "doLists" => 40,
        "doCodeBlocks" => 50,
        "doBlockQuotes" => 60,
    );
    protected $em_relist = array(
        '' => '(?:(?<!\*)\*(?!\*)|(?<!_)_(?!_))(?=\S|$)(?![.,:;]\s)',
        '*' => '(?<=\S|^)(?<!\*)\*(?!\*)',
        '_' => '(?<=\S|^)(?<!_)_(?!_)',
    );
    protected $strong_relist = array(
        '' => '(?:(?<!\*)\*\*(?!\*)|(?<!_)__(?!_))(?=\S|$)(?![.,:;]\s)',
        '**' => '(?<=\S|^)(?<!\*)\*\*(?!\*)',
        '__' => '(?<=\S|^)(?<!_)__(?!_)',
    );
    protected $em_strong_relist = array(
        '' => '(?:(?<!\*)\*\*\*(?!\*)|(?<!_)___(?!_))(?=\S|$)(?![.,:;]\s)',
        '***' => '(?<=\S|^)(?<!\*)\*\*\*(?!\*)',
        '___' => '(?<=\S|^)(?<!_)___(?!_)',
    );
    protected $em_strong_prepared_relist;
    protected $list_level = 0;

    /**
     * Constructor function.
     * Initialize appropriate member variables.
     */
    public function __construct() {

        $this->_initDetab();
        $this->prepareItalicsAndBold();

        $this->nested_brackets_re =
                str_repeat('(?>[^\[\]]+|\[', $this->nested_brackets_depth) .
                str_repeat('\])*', $this->nested_brackets_depth);

        $this->nested_url_parenthesis_re =
                str_repeat('(?>[^()\s]+|\(', $this->nested_url_parenthesis_depth) .
                str_repeat('(?>\)))*', $this->nested_url_parenthesis_depth);

        $this->escape_chars_re = '[' . preg_quote($this->escape_chars) . ']';

        // Sort document, block, and span gamut in ascendent priority order.
        asort($this->document_gamut);
        asort($this->block_gamut);
        asort($this->span_gamut);
    }

    /**
     * Called before the transformation process starts to setup parser
     * states.
     * Clear global hashes.
     */
    protected function setup() {

        $this->urls = $this->predef_urls;
        $this->titles = $this->predef_titles;
        $this->html_hashes = array();

        $in_anchor = false;
    }

    /**
     * Called after the transformation
     * process to clear any variable
     * which may be taking up memory unnecessarly.
     */
    protected function teardown() {
        $this->urls = array();
        $this->titles = array();
        $this->html_hashes = array();
    }

    public function transform($text) {
        #
        # Main function. Performs some preprocessing on the input text
        # and pass it through the document gamut.
        #
		$this->setup();

        # Remove UTF-8 BOM and marker character in input, if present.
        $text = preg_replace('{^\xEF\xBB\xBF|\x1A}', '', $text);

        # Standardize line endings:
        #   DOS to Unix and Mac to Unix
        $text = preg_replace('{\r\n?}', "\n", $text);

        # Make sure $text ends with a couple of newlines:
        $text .= "\n\n";

        # Convert all tabs to spaces.
        $text = $this->detab($text);

        # Turn block-level HTML blocks into hash entries
        $text = $this->hashHTMLBlocks($text);

        # Strip any lines consisting only of spaces and tabs.
        # This makes subsequent regexen easier to write, because we can
        # match consecutive blank lines with /\n+/ instead of something
        # contorted like /[ ]*\n+/ .
        $text = preg_replace('/^[ ]+$/m', '', $text);

        # Run document gamut methods.
        foreach ($this->document_gamut as $method => $priority) {
            $text = $this->$method($text);
        }

        $this->teardown();

        return $text . "\n";
    }

    protected function stripLinkDefinitions($text) {
        #
        # Strips link definitions from text, stores the URLs and titles in
        # hash references.
        #
		$less_than_tab = $this->tab_width - 1;

        # Link defs are in the form: ^[id]: url "optional title"
        $text = preg_replace_callback('{
							^[ ]{0,' . $less_than_tab . '}\[(.+)\][ ]?:	# id = $1
							  [ ]*
							  \n?				# maybe *one* newline
							  [ ]*
							(?:
							  <(.+?)>			# url = $2
							|
							  (\S+?)			# url = $3
							)
							  [ ]*
							  \n?				# maybe one newline
							  [ ]*
							(?:
								(?<=\s)			# lookbehind for whitespace
								["(]
								(.*?)			# title = $4
								[")]
								[ ]*
							)?	# title is optional
							(?:\n+|\Z)
			}xm', array($this, '_stripLinkDefinitions_callback'), $text);

        return $text;
    }

    protected function _stripLinkDefinitions_callback($matches) {
        $link_id = strtolower($matches[1]);
        $url = $matches[2] == '' ? $matches[3] : $matches[2];
        $this->urls[$link_id] = $url;
        $this->titles[$link_id] = & $matches[4];

        return ''; # String that will replace the block
    }

    protected function hashHTMLBlocks($text) {
        if ($this->no_markup)
            return $text;

        $less_than_tab = $this->tab_width - 1;

        # Hashify HTML blocks:
        # We only want to do this for block-level HTML tags, such as headers,
        # lists, and tables. That's because we still want to wrap <p>s around
        # "paragraphs" that are wrapped in non-block-level tags, such as anchors,
        # phrase emphasis, and spans. The list of tags we're looking for is
        # hard-coded:
        #
		# *  List "a" is made of tags which can be both inline or block-level.
        #    These will be treated block-level when the start tag is alone on
        #    its line, otherwise they're not matched here and will be taken as
        #    inline later.
        # *  List "b" is made of tags which are always block-level;
        #
		$block_tags_a_re = 'ins|del';
        $block_tags_b_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|' .
                'script|noscript|form|fieldset|iframe|math';

        # Regular expression for the content of a block tag.
        $nested_tags_level = 4;
        $attr = '
			(?>				# optional tag attributes
			  \s			# starts with whitespace
			  (?>
				[^>"/]+		# text outside quotes
			  |
				/+(?!>)		# slash not followed by ">"
			  |
				"[^"]*"		# text inside double quotes (tolerate ">")
			  |
				\'[^\']*\'	# text inside single quotes (tolerate ">")
			  )*
			)?	
			';
        $content =
                str_repeat('
				(?>
				  [^<]+			# content without tag
				|
				  <\2			# nested opening tag
					' . $attr . '	# attributes
					(?>
					  />
					|
					  >', $nested_tags_level) . # end of opening tag
                '.*?' . # last level nested tag content
                str_repeat('
					  </\2\s*>	# closing nested tag
					)
				  |				
					<(?!/\2\s*>	# other tags with a different name
				  )
				)*', $nested_tags_level);
        $content2 = str_replace('\2', '\3', $content);

        # First, look for nested blocks, e.g.:
        # 	<div>
        # 		<div>
        # 		tags for inner block must be indented.
        # 		</div>
        # 	</div>
        #
		# The outermost tags must start at the left margin for this to match, and
        # the inner nested divs must be indented.
        # We need to do this before the next, more liberal match, because the next
        # match will start at the first `<div>` and stop at the first `</div>`.
        $text = preg_replace_callback('{(?>
			(?>
				(?<=\n\n)		# Starting after a blank line
				|				# or
				\A\n?			# the beginning of the doc
			)
			(						# save in $1

			  # Match from `\n<tag>` to `</tag>\n`, handling nested tags 
			  # in between.
					
						[ ]{0,' . $less_than_tab . '}
						<(' . $block_tags_b_re . ')# start tag = $2
						' . $attr . '>			# attributes followed by > and \n
						' . $content . '		# content, support nesting
						</\2>				# the matching end tag
						[ ]*				# trailing spaces/tabs
						(?=\n+|\Z)	# followed by a newline or end of document

			| # Special version for tags of group a.

						[ ]{0,' . $less_than_tab . '}
						<(' . $block_tags_a_re . ')# start tag = $3
						' . $attr . '>[ ]*\n	# attributes followed by >
						' . $content2 . '		# content, support nesting
						</\3>				# the matching end tag
						[ ]*				# trailing spaces/tabs
						(?=\n+|\Z)	# followed by a newline or end of document
					
			| # Special case just for <hr />. It was easier to make a special 
			  # case than to make the other regex more complicated.
			
						[ ]{0,' . $less_than_tab . '}
						<(hr)				# start tag = $2
						' . $attr . '			# attributes
						/?>					# the matching end tag
						[ ]*
						(?=\n{2,}|\Z)		# followed by a blank line or end of document
			
			| # Special case for standalone HTML comments:
			
					[ ]{0,' . $less_than_tab . '}
					(?s:
						<!-- .*? -->
					)
					[ ]*
					(?=\n{2,}|\Z)		# followed by a blank line or end of document
			
			| # PHP and ASP-style processor instructions (<? and <%)
			
					[ ]{0,' . $less_than_tab . '}
					(?s:
						<([?%])			# $2
						.*?
						\2>
					)
					[ ]*
					(?=\n{2,}|\Z)		# followed by a blank line or end of document
					
			)
			)}Sxmi', array($this, '_hashHTMLBlocks_callback'), $text);

        return $text;
    }

    protected function _hashHTMLBlocks_callback($matches) {
        $text = $matches[1];
        $key = $this->hashBlock($text);
        return "\n\n$key\n\n";
    }

    protected function hashPart($text, $boundary = 'X') {
        #
        # Called whenever a tag must be hashed when a protected function insert an atomic
        # element in the text stream. Passing $text to through this protected function gives
        # a unique text-token which will be reverted back when calling unhash.
        #
		# The $boundary argument specify what character should be used to surround
        # the token. By convension, "B" is used for block elements that needs not
        # to be wrapped into paragraph tags at the end, ":" is used for elements
        # that are word separators and "X" is used in the general case.
        #
		# Swap back any tag hash found in $text so we do not have to `unhash`
        # multiple times at the end.
        $text = $this->unhash($text);

        # Then hash the block.
        static $i = 0;
        $key = "$boundary\x1A" . ++$i . $boundary;
        $this->html_hashes[$key] = $text;
        return $key; # String that will replace the tag.
    }

    protected function hashBlock($text) {
        #
        # Shortcut protected function for hashPart with block-level boundaries.
        #
		return $this->hashPart($text, 'B');
    }

    protected function runBlockGamut($text) {
        #
        # Run block gamut tranformations.
        #
		# We need to escape raw HTML in Markdown source before doing anything
        # else. This need to be done for each block, and not only at the
        # begining in the Markdown protected function since hashed blocks can be part of
        # list items and could have been indented. Indented blocks would have
        # been seen as a code block in a previous pass of hashHTMLBlocks.
        $text = $this->hashHTMLBlocks($text);

        return $this->runBasicBlockGamut($text);
    }

    protected function runBasicBlockGamut($text) {
        #
        # Run block gamut tranformations, without hashing HTML blocks. This is
        # useful when HTML blocks are known to be already hashed, like in the first
        # whole-document pass.
        #
		foreach ($this->block_gamut as $method => $priority) {
            $text = $this->$method($text);
        }

        # Finally form paragraph and restore hashed blocks.
        $text = $this->formParagraphs($text);

        return $text;
    }

    protected function doHorizontalRules($text) {
        # Do Horizontal Rules:
        return preg_replace(
                        '{
				^[ ]{0,3}	# Leading space
				([-*_])		# $1: First marker
				(?>			# Repeated marker group
					[ ]{0,2}	# Zero, one, or two spaces.
					\1			# Marker character
				){2,}		# Group repeated at least twice
				[ ]*		# Tailing spaces
				$			# End of line.
			}mx', "\n" . $this->hashBlock("<hr$this->empty_element_suffix") . "\n", $text);
    }

    protected $span_gamut = array(
        #
        # These are all the transformations that occur *within* block-level
        # tags like paragraphs, headers, and list items.
        #
	# Process character escapes, code spans, and inline HTML
        # in one shot.
        "parseSpan" => -30,
        # Process anchor and image tags. Images must come first,
        # because ![foo][f] looks like an anchor.
        "doImages" => 10,
        "doAnchors" => 20,
        # Make links out of things like `<http://example.com/>`
        # Must come after doAnchors, because you can use < and >
        # delimiters in inline links like [this](<url>).
        "doAutoLinks" => 30,
        "encodeAmpsAndAngles" => 40,
        "doItalicsAndBold" => 50,
        "doHardBreaks" => 60,
    );

    protected function runSpanGamut($text) {
        #
        # Run span gamut tranformations.
        #
		foreach ($this->span_gamut as $method => $priority) {
            $text = $this->$method($text);
        }

        return $text;
    }

    protected function doHardBreaks($text) {
        # Do hard breaks:
        return preg_replace_callback('/ {2,}\n/', array($this, '_doHardBreaks_callback'), $text);
    }

    protected function _doHardBreaks_callback($matches) {
        return $this->hashPart("<br$this->empty_element_suffix\n");
    }

    protected function doAnchors($text) {
        #
        # Turn Markdown link shortcuts into XHTML <a> tags.
        #
		if ($this->in_anchor)
            return $text;
        $this->in_anchor = true;

        #
        # First, handle reference-style links: [link text] [id]
        #
		$text = preg_replace_callback('{
			(					# wrap whole match in $1
			  \[
				(' . $this->nested_brackets_re . ')	# link text = $2
			  \]

			  [ ]?				# one optional space
			  (?:\n[ ]*)?		# one optional newline followed by spaces

			  \[
				(.*?)		# id = $3
			  \]
			)
			}xs', array($this, '_doAnchors_reference_callback'), $text);

        #
        # Next, inline-style links: [link text](url "optional title")
        #
		$text = preg_replace_callback('{
			(				# wrap whole match in $1
			  \[
				(' . $this->nested_brackets_re . ')	# link text = $2
			  \]
			  \(			# literal paren
				[ \n]*
				(?:
					<(.+?)>	# href = $3
				|
					(' . $this->nested_url_parenthesis_re . ')	# href = $4
				)
				[ \n]*
				(			# $5
				  ([\'"])	# quote char = $6
				  (.*?)		# Title = $7
				  \6		# matching quote
				  [ \n]*	# ignore any spaces/tabs between closing quote and )
				)?			# title is optional
			  \)
			)
			}xs', array($this, '_doAnchors_inline_callback'), $text);

        #
        # Last, handle reference-style shortcuts: [link text]
        # These must come last in case you've also got [link text][1]
        # or [link text](/foo)
        #
		$text = preg_replace_callback('{
			(					# wrap whole match in $1
			  \[
				([^\[\]]+)		# link text = $2; can\'t contain [ or ]
			  \]
			)
			}xs', array($this, '_doAnchors_reference_callback'), $text);

        $this->in_anchor = false;
        return $text;
    }

    protected function _doAnchors_reference_callback($matches) {
        $whole_match = $matches[1];
        $link_text = $matches[2];
        $link_id = & $matches[3];

        if ($link_id == "") {
            # for shortcut links like [this][] or [this].
            $link_id = $link_text;
        }

        # lower-case and turn embedded newlines into spaces
        $link_id = strtolower($link_id);
        $link_id = preg_replace('{[ ]?\n}', ' ', $link_id);

        if (isset($this->urls[$link_id])) {
            $url = $this->urls[$link_id];
            $url = $this->encodeAttribute($url);

            $result = "<a href=\"$url\"";
            if (isset($this->titles[$link_id])) {
                $title = $this->titles[$link_id];
                $title = $this->encodeAttribute($title);
                $result .= " title=\"$title\"";
            }

            $link_text = $this->runSpanGamut($link_text);
            $result .= ">$link_text</a>";
            $result = $this->hashPart($result);
        } else {
            $result = $whole_match;
        }

        return $result;
    }

    protected function _doAnchors_inline_callback($matches) {
        $whole_match = $matches[1];
        $link_text = $this->runSpanGamut($matches[2]);
        $url = $matches[3] == '' ? $matches[4] : $matches[3];
        $title = & $matches[7];

        $url = $this->encodeAttribute($url);

        $result = "<a href=\"$url\"";
        if (isset($title)) {
            $title = $this->encodeAttribute($title);
            $result .= " title=\"$title\"";
        }

        $link_text = $this->runSpanGamut($link_text);
        $result .= ">$link_text</a>";

        return $this->hashPart($result);
    }

    protected function doImages($text) {
        #
        # Turn Markdown image shortcuts into <img> tags.
        #
		#
		# First, handle reference-style labeled images: ![alt text][id]
        #
		$text = preg_replace_callback('{
			(				# wrap whole match in $1
			  !\[
				(' . $this->nested_brackets_re . ')		# alt text = $2
			  \]

			  [ ]?				# one optional space
			  (?:\n[ ]*)?		# one optional newline followed by spaces

			  \[
				(.*?)		# id = $3
			  \]

			)
			}xs', array($this, '_doImages_reference_callback'), $text);

        #
        # Next, handle inline images:  ![alt text](url "optional title")
        # Don't forget: encode * and _
        #
		$text = preg_replace_callback('{
			(				# wrap whole match in $1
			  !\[
				(' . $this->nested_brackets_re . ')		# alt text = $2
			  \]
			  \s?			# One optional whitespace character
			  \(			# literal paren
				[ \n]*
				(?:
					<(\S*)>	# src url = $3
				|
					(' . $this->nested_url_parenthesis_re . ')	# src url = $4
				)
				[ \n]*
				(			# $5
				  ([\'"])	# quote char = $6
				  (.*?)		# title = $7
				  \6		# matching quote
				  [ \n]*
				)?			# title is optional
			  \)
			)
			}xs', array($this, '_doImages_inline_callback'), $text);

        return $text;
    }

    protected function _doImages_reference_callback($matches) {
        $whole_match = $matches[1];
        $alt_text = $matches[2];
        $link_id = strtolower($matches[3]);

        if ($link_id == "") {
            $link_id = strtolower($alt_text); # for shortcut links like ![this][].
        }

        $alt_text = $this->encodeAttribute($alt_text);
        if (isset($this->urls[$link_id])) {
            $url = $this->encodeAttribute($this->urls[$link_id]);
            $result = "<img src=\"$url\" alt=\"$alt_text\"";
            if (isset($this->titles[$link_id])) {
                $title = $this->titles[$link_id];
                $title = $this->encodeAttribute($title);
                $result .= " title=\"$title\"";
            }
            $result .= $this->empty_element_suffix;
            $result = $this->hashPart($result);
        } else {
            # If there's no such link ID, leave intact:
            $result = $whole_match;
        }

        return $result;
    }

    protected function _doImages_inline_callback($matches) {
        $whole_match = $matches[1];
        $alt_text = $matches[2];
        $url = $matches[3] == '' ? $matches[4] : $matches[3];
        $title = & $matches[7];

        $alt_text = $this->encodeAttribute($alt_text);
        $url = $this->encodeAttribute($url);
        $result = "<img src=\"$url\" alt=\"$alt_text\"";
        if (isset($title)) {
            $title = $this->encodeAttribute($title);
            $result .= " title=\"$title\""; # $title already quoted
        }
        $result .= $this->empty_element_suffix;

        return $this->hashPart($result);
    }

    protected function doHeaders($text) {
        # Setext-style headers:
        #	  Header 1
        #	  ========
        #
		#	  Header 2
        #	  --------
        #
		$text = preg_replace_callback('{ ^(.+?)[ ]*\n(=+|-+)[ ]*\n+ }mx', array($this, '_doHeaders_callback_setext'), $text);

        # atx-style headers:
        #	# Header 1
        #	## Header 2
        #	## Header 2 with closing hashes ##
        #	...
        #	###### Header 6
        #
		$text = preg_replace_callback('{
				^(\#{1,6})	# $1 = string of #\'s
				[ ]*
				(.+?)		# $2 = Header text
				[ ]*
				\#*			# optional closing #\'s (not counted)
				\n+
			}xm', array($this, '_doHeaders_callback_atx'), $text);

        return $text;
    }

    protected function _doHeaders_callback_setext($matches) {
        # Terrible hack to check we haven't found an empty list item.
        if ($matches[2] == '-' && preg_match('{^-(?: |$)}', $matches[1]))
            return $matches[0];

        $level = $matches[2]{0} == '=' ? 1 : 2;
        $block = "<h$level>" . $this->runSpanGamut($matches[1]) . "</h$level>";
        return "\n" . $this->hashBlock($block) . "\n\n";
    }

    protected function _doHeaders_callback_atx($matches) {
        $level = strlen($matches[1]);
        $block = "<h$level>" . $this->runSpanGamut($matches[2]) . "</h$level>";
        return "\n" . $this->hashBlock($block) . "\n\n";
    }

    protected function doLists($text) {
        #
        # Form HTML ordered (numbered) and unordered (bulleted) lists.
        #
		$less_than_tab = $this->tab_width - 1;

        # Re-usable patterns to match list item bullets and number markers:
        $marker_ul_re = '[*+-]';
        $marker_ol_re = '\d+[.]';
        $marker_any_re = "(?:$marker_ul_re|$marker_ol_re)";

        $markers_relist = array(
            $marker_ul_re => $marker_ol_re,
            $marker_ol_re => $marker_ul_re,
        );

        foreach ($markers_relist as $marker_re => $other_marker_re) {
            # Re-usable pattern to match any entirel ul or ol list:
            $whole_list_re = '
				(								# $1 = whole list
				  (								# $2
					([ ]{0,' . $less_than_tab . '})	# $3 = number of spaces
					(' . $marker_re . ')			# $4 = first list item marker
					[ ]+
				  )
				  (?s:.+?)
				  (								# $5
					  \z
					|
					  \n{2,}
					  (?=\S)
					  (?!						# Negative lookahead for another list item marker
						[ ]*
						' . $marker_re . '[ ]+
					  )
					|
					  (?=						# Lookahead for another kind of list
					    \n
						\3						# Must have the same indentation
						' . $other_marker_re . '[ ]+
					  )
				  )
				)
			'; // mx
            # We use a different prefix before nested lists than top-level lists.
            # See extended comment in _ProcessListItems().

            if ($this->list_level) {
                $text = preg_replace_callback('{
						^
						' . $whole_list_re . '
					}mx', array($this, '_doLists_callback'), $text);
            } else {
                $text = preg_replace_callback('{
						(?:(?<=\n)\n|\A\n?) # Must eat the newline
						' . $whole_list_re . '
					}mx', array($this, '_doLists_callback'), $text);
            }
        }

        return $text;
    }

    protected function _doLists_callback($matches) {
        # Re-usable patterns to match list item bullets and number markers:
        $marker_ul_re = '[*+-]';
        $marker_ol_re = '\d+[.]';
        $marker_any_re = "(?:$marker_ul_re|$marker_ol_re)";

        $list = $matches[1];
        $list_type = preg_match("/$marker_ul_re/", $matches[4]) ? "ul" : "ol";

        $marker_any_re = ( $list_type == "ul" ? $marker_ul_re : $marker_ol_re );

        $list .= "\n";
        $result = $this->processListItems($list, $marker_any_re);

        $result = $this->hashBlock("<$list_type>\n" . $result . "</$list_type>");
        return "\n" . $result . "\n\n";
    }

    protected function processListItems($list_str, $marker_any_re) {
        #
        #	Process the contents of a single ordered or unordered list, splitting it
        #	into individual list items.
        #
		# The $this->list_level global keeps track of when we're inside a list.
        # Each time we enter a list, we increment it; when we leave a list,
        # we decrement. If it's zero, we're not in a list anymore.
        #
		# We do this because when we're not inside a list, we want to treat
        # something like this:
        #
		#		I recommend upgrading to version
        #		8. Oops, now this line is treated
        #		as a sub-list.
        #
		# As a single paragraph, despite the fact that the second line starts
        # with a digit-period-space sequence.
        #
		# Whereas when we're inside a list (or sub-list), that line will be
        # treated as the start of a sub-list. What a kludge, huh? This is
        # an aspect of Markdown's syntax that's hard to parse perfectly
        # without resorting to mind-reading. Perhaps the solution is to
        # change the syntax rules such that sub-lists must start with a
        # starting cardinal number; e.g. "1." or "a.".

        $this->list_level++;

        # trim trailing blank lines:
        $list_str = preg_replace("/\n{2,}\\z/", "\n", $list_str);

        $list_str = preg_replace_callback('{
			(\n)?							# leading line = $1
			(^[ ]*)							# leading whitespace = $2
			(' . $marker_any_re . '				# list marker and space = $3
				(?:[ ]+|(?=\n))	# space only required if item is not empty
			)
			((?s:.*?))						# list item text   = $4
			(?:(\n+(?=\n))|\n)				# tailing blank line = $5
			(?= \n* (\z | \2 (' . $marker_any_re . ') (?:[ ]+|(?=\n))))
			}xm', array($this, '_processListItems_callback'), $list_str);

        $this->list_level--;

        return $list_str;
    }

    protected function _processListItems_callback($matches) {
        $item = $matches[4];
        $leading_line = & $matches[1];
        $leading_space = & $matches[2];
        $marker_space = $matches[3];
        $tailing_blank_line = & $matches[5];

        if ($leading_line || $tailing_blank_line ||
                preg_match('/\n{2,}/', $item)) {
            # Replace marker with the appropriate whitespace indentation
            $item = $leading_space . str_repeat(' ', strlen($marker_space)) . $item;
            $item = $this->runBlockGamut($this->outdent($item) . "\n");
        } else {
            # Recursion for sub-lists:
            $item = $this->doLists($this->outdent($item));
            $item = preg_replace('/\n+$/', '', $item);
            $item = $this->runSpanGamut($item);
        }

        return "<li>" . $item . "</li>\n";
    }

    protected function doCodeBlocks($text) {
        #
        #	Process Markdown `<pre><code>` blocks.
        #
		$text = preg_replace_callback('{
				(?:\n\n|\A\n?)
				(	            # $1 = the code block -- one or more lines, starting with a space/tab
				  (?>
					[ ]{' . $this->tab_width . '}  # Lines must start with a tab or a tab-width of spaces
					.*\n+
				  )+
				)
				((?=^[ ]{0,' . $this->tab_width . '}\S)|\Z)	# Lookahead for non-space at line-start, or end of doc
			}xm', array($this, '_doCodeBlocks_callback'), $text);

        return $text;
    }

    protected function _doCodeBlocks_callback($matches) {
        $codeblock = $matches[1];

        $codeblock = $this->outdent($codeblock);
        $codeblock = htmlspecialchars($codeblock, ENT_NOQUOTES);

        # trim leading newlines and trailing newlines
        $codeblock = preg_replace('/\A\n+|\n+\z/', '', $codeblock);

        $codeblock = "<pre><code>$codeblock\n</code></pre>";

        return "\n\n" . $this->hashBlock($codeblock) . "\n\n";
    }

    protected function makeCodeSpan($code) {
        #
        # Create a code span markup for $code. Called from handleSpanToken.
        #
		$code = htmlspecialchars(trim($code), ENT_NOQUOTES);
        return $this->hashPart("<code>$code</code>");
    }

    protected function prepareItalicsAndBold() {
        #
        # Prepare regular expressions for searching emphasis tokens in any
        # context.
        #
		foreach ($this->em_relist as $em => $em_re) {
            foreach ($this->strong_relist as $strong => $strong_re) {
                # Construct list of allowed token expressions.
                $token_relist = array();
                if (isset($this->em_strong_relist["$em$strong"])) {
                    $token_relist[] = $this->em_strong_relist["$em$strong"];
                }
                $token_relist[] = $em_re;
                $token_relist[] = $strong_re;

                # Construct master expression from list.
                $token_re = '{(' . implode('|', $token_relist) . ')}';
                $this->em_strong_prepared_relist["$em$strong"] = $token_re;
            }
        }
    }

    protected function doItalicsAndBold($text) {
        $token_stack = array('');
        $text_stack = array('');
        $em = '';
        $strong = '';
        $tree_char_em = false;

        while (true) {
            #
            # Get prepared regular expression for seraching emphasis tokens
            # in current context.
            #
			$token_re = $this->em_strong_prepared_relist["$em$strong"];

            d('$token_re: ' . $token_re . ' $text: ' . $text);

            #
            # Each loop iteration search for the next emphasis token.
            # Each token is then passed to handleSpanToken.
            #
			$parts = preg_split($token_re, $text, 2, PREG_SPLIT_DELIM_CAPTURE);
            $text_stack[0] .= $parts[0];
            $token = & $parts[1];
            $text = & $parts[2];

            if (empty($token)) {
                # Reached end of text span: empty stack without emitting.
                # any more emphasis.
                while ($token_stack[0]) {
                    $text_stack[1] .= array_shift($token_stack);
                    $text_stack[0] .= array_shift($text_stack);
                }
                break;
            }

            $token_len = strlen($token);
            if ($tree_char_em) {
                # Reached closing marker while inside a three-char emphasis.
                if ($token_len == 3) {
                    # Three-char closing marker, close em and strong.
                    array_shift($token_stack);
                    $span = array_shift($text_stack);
                    $span = $this->runSpanGamut($span);
                    $span = "<strong><em>$span</em></strong>";
                    $text_stack[0] .= $this->hashPart($span);
                    $em = '';
                    $strong = '';
                } else {
                    # Other closing marker: close one em or strong and
                    # change current token state to match the other
                    $token_stack[0] = str_repeat($token{0}, 3 - $token_len);
                    $tag = $token_len == 2 ? "strong" : "em";
                    $span = $text_stack[0];
                    $span = $this->runSpanGamut($span);
                    $span = "<$tag>$span</$tag>";
                    $text_stack[0] = $this->hashPart($span);
                    $$tag = ''; # $$tag stands for $em or $strong
                }
                $tree_char_em = false;
            } else if ($token_len == 3) {
                if ($em) {
                    # Reached closing marker for both em and strong.
                    # Closing strong marker:
                    for ($i = 0; $i < 2; ++$i) {
                        $shifted_token = array_shift($token_stack);
                        $tag = strlen($shifted_token) == 2 ? "strong" : "em";
                        $span = array_shift($text_stack);
                        $span = $this->runSpanGamut($span);
                        $span = "<$tag>$span</$tag>";
                        $text_stack[0] .= $this->hashPart($span);
                        $$tag = ''; # $$tag stands for $em or $strong
                    }
                } else {
                    # Reached opening three-char emphasis marker. Push on token
                    # stack; will be handled by the special condition above.
                    $em = $token{0};
                    $strong = "$em$em";
                    array_unshift($token_stack, $token);
                    array_unshift($text_stack, '');
                    $tree_char_em = true;
                }
            } else if ($token_len == 2) {
                if ($strong) {
                    # Unwind any dangling emphasis marker:
                    if (strlen($token_stack[0]) == 1) {
                        $text_stack[1] .= array_shift($token_stack);
                        $text_stack[0] .= array_shift($text_stack);
                    }
                    # Closing strong marker:
                    array_shift($token_stack);
                    $span = array_shift($text_stack);
                    $span = $this->runSpanGamut($span);
                    $span = "<strong>$span</strong>";
                    $text_stack[0] .= $this->hashPart($span);
                    $strong = '';
                } else {
                    array_unshift($token_stack, $token);
                    array_unshift($text_stack, '');
                    $strong = $token;
                }
            } else {
                # Here $token_len == 1
                if ($em) {
                    if (strlen($token_stack[0]) == 1) {
                        # Closing emphasis marker:
                        array_shift($token_stack);
                        $span = array_shift($text_stack);
                        $span = $this->runSpanGamut($span);
                        $span = "<em>$span</em>";
                        $text_stack[0] .= $this->hashPart($span);
                        $em = '';
                    } else {
                        $text_stack[0] .= $token;
                    }
                } else {
                    array_unshift($token_stack, $token);
                    array_unshift($text_stack, '');
                    $em = $token;
                }
            }
        }
        return $text_stack[0];
    }

    protected function doBlockQuotes($text) {
        $text = preg_replace_callback('/
			  (								# Wrap whole match in $1
				(?>
				  ^[ ]*>[ ]?			# ">" at the start of a line
					.+\n					# rest of the first line
				  (.+\n)*					# subsequent consecutive lines
				  \n*						# blanks
				)+
			  )
			/xm', array($this, '_doBlockQuotes_callback'), $text);

        return $text;
    }

    protected function _doBlockQuotes_callback($matches) {
        $bq = $matches[1];
        # trim one level of quoting - trim whitespace-only lines
        $bq = preg_replace('/^[ ]*>[ ]?|^[ ]+$/m', '', $bq);
        $bq = $this->runBlockGamut($bq);  # recurse

        $bq = preg_replace('/^/m', "  ", $bq);
        # These leading spaces cause problem with <pre> content,
        # so we need to fix that:
        $bq = preg_replace_callback('{(\s*<pre>.+?</pre>)}sx', array($this, '_doBlockQuotes_callback2'), $bq);

        return "\n" . $this->hashBlock("<blockquote>\n$bq\n</blockquote>") . "\n\n";
    }

    protected function _doBlockQuotes_callback2($matches) {
        $pre = $matches[1];
        $pre = preg_replace('/^  /m', '', $pre);
        return $pre;
    }

    protected function formParagraphs($text) {
        #
        #	Params:
        #		$text - string to process with html <p> tags
        #
		# Strip leading and trailing lines:
        $text = preg_replace('/\A\n+|\n+\z/', '', $text);

        $grafs = preg_split('/\n{2,}/', $text, -1, PREG_SPLIT_NO_EMPTY);

        #
        # Wrap <p> tags and unhashify HTML blocks
        #
		foreach ($grafs as $key => $value) {
            if (!preg_match('/^B\x1A[0-9]+B$/', $value)) {
                # Is a paragraph.
                $value = $this->runSpanGamut($value);
                $value = preg_replace('/^([ ]*)/', "<p>", $value);
                $value .= "</p>";
                $grafs[$key] = $this->unhash($value);
            } else {
                # Is a block.
                # Modify elements of @grafs in-place...
                $graf = $value;
                $block = $this->html_hashes[$graf];
                $graf = $block;
                //				if (preg_match('{
                //					\A
                //					(							# $1 = <div> tag
                //					  <div  \s+
                //					  [^>]*
                //					  \b
                //					  markdown\s*=\s*  ([\'"])	#	$2 = attr quote char
                //					  1
                //					  \2
                //					  [^>]*
                //					  >
                //					)
                //					(							# $3 = contents
                //					.*
                //					)
                //					(</div>)					# $4 = closing tag
                //					\z
                //					}xs', $block, $matches))
                //				{
                //					list(, $div_open, , $div_content, $div_close) = $matches;
                //
				//					# We can't call Markdown(), because that resets the hash;
                //					# that initialization code should be pulled into its own sub, though.
                //					$div_content = $this->hashHTMLBlocks($div_content);
                //
				//					# Run document gamut methods on the content.
                //					foreach ($this->document_gamut as $method => $priority) {
                //						$div_content = $this->$method($div_content);
                //					}
                //
				//					$div_open = preg_replace(
                //						'{\smarkdown\s*=\s*([\'"]).+?\1}', '', $div_open);
                //
				//					$graf = $div_open . "\n" . $div_content . "\n" . $div_close;
                //				}
                $grafs[$key] = $graf;
            }
        }

        return implode("\n\n", $grafs);
    }

    protected function encodeAttribute($text) {
        #
        # Encode text for a double-quoted HTML attribute. This function
        # is *not* suitable for attributes enclosed in single quotes.
        #
		$text = $this->encodeAmpsAndAngles($text);
        $text = str_replace('"', '&quot;', $text);
        return $text;
    }

    protected function encodeAmpsAndAngles($text) {
        #
        # Smart processing for ampersands and angle brackets that need to
        # be encoded. Valid character entities are left alone unless the
        # no-entities mode is set.
        #
		if ($this->no_entities) {
            $text = str_replace('&', '&amp;', $text);
        } else {
            # Ampersand-encoding based entirely on Nat Irons's Amputator
            # MT plugin: <http://bumppo.net/projects/amputator/>
            $text = preg_replace('/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/', '&amp;', $text);
            ;
        }
        # Encode remaining <'s
        $text = str_replace('<', '&lt;', $text);

        return $text;
    }

    protected function doAutoLinks($text) {
        $text = preg_replace_callback('{<((https?|ftp|dict):[^\'">\s]+)>}i', array($this, '_doAutoLinks_url_callback'), $text);

        # Email addresses: <address@domain.foo>
        $text = preg_replace_callback('{
			<
			(?:mailto:)?
			(
				(?:
					[-!#$%&\'*+/=?^_`.{|}~\w\x80-\xFF]+
				|
					".*?"
				)
				\@
				(?:
					[-a-z0-9\x80-\xFF]+(\.[-a-z0-9\x80-\xFF]+)*\.[a-z]+
				|
					\[[\d.a-fA-F:]+\]	# IPv4 & IPv6
				)
			)
			>
			}xi', array($this, '_doAutoLinks_email_callback'), $text);

        return $text;
    }

    protected function _doAutoLinks_url_callback($matches) {
        $url = $this->encodeAttribute($matches[1]);
        $link = "<a href=\"$url\">$url</a>";

        return $this->hashPart($link);
    }

    protected function _doAutoLinks_email_callback($matches) {
        $address = $matches[1];
        $link = $this->encodeEmailAddress($address);

        return $this->hashPart($link);
    }

    protected function encodeEmailAddress($addr) {
        #
        #	Input: an email address, e.g. "foo@example.com"
        #
		#	Output: the email address as a mailto link, with each character
        #		of the address encoded as either a decimal or hex entity, in
        #		the hopes of foiling most address harvesting spam bots. E.g.:
        #
		#	  <p><a href="&#109;&#x61;&#105;&#x6c;&#116;&#x6f;&#58;&#x66;o&#111;
        #        &#x40;&#101;&#x78;&#97;&#x6d;&#112;&#x6c;&#101;&#46;&#x63;&#111;
        #        &#x6d;">&#x66;o&#111;&#x40;&#101;&#x78;&#97;&#x6d;&#112;&#x6c;
        #        &#101;&#46;&#x63;&#111;&#x6d;</a></p>
        #
		#	Based by a filter by Matthew Wickline, posted to BBEdit-Talk.
        #   With some optimizations by Milian Wolff.
        #
		$addr = "mailto:" . $addr;
        $chars = preg_split('/(?<!^)(?!$)/', $addr);
        $seed = (int) abs(crc32($addr) / strlen($addr)); # Deterministic seed.

        foreach ($chars as $key => $char) {
            $ord = ord($char);
            # Ignore non-ascii chars.
            if ($ord < 128) {
                $r = ($seed * (1 + $key)) % 100; # Pseudo-random function.
                # roughly 10% raw, 45% hex, 45% dec
                # '@' *must* be encoded. I insist.
                if ($r > 90 && $char != '@') /* do nothing */
                    ;
                else if ($r < 45)
                    $chars[$key] = '&#x' . dechex($ord) . ';';
                else
                    $chars[$key] = '&#' . $ord . ';';
            }
        }

        $addr = implode('', $chars);
        $text = implode('', array_slice($chars, 7)); # text without `mailto:`
        $addr = "<a href=\"$addr\" target=\"_blank\" rel=\"nofollow\">$text</a>";

        return $addr;
    }

    protected function parseSpan($str) {
        #
        # Take the string $str and parse it into tokens, hashing embeded HTML,
        # escaped characters and handling code spans.
        #
		$output = '';

        $span_re = '{
				(
					\\\\' . $this->escape_chars_re . '
				|
					(?<![`\\\\])
					`+						# code span marker
			' . ( $this->no_markup ? '' : '
				|
					<!--    .*?     -->		# comment
				|
					<\?.*?\?> | <%.*?%>		# processing instruction
				|
					<[/!$]?[-a-zA-Z0-9:_]+	# regular tags
					(?>
						\s
						(?>[^"\'>]+|"[^"]*"|\'[^\']*\')*
					)?
					>
			') . '
				)
				}xs';

        while (1) {
            #
            # Each loop iteration seach for either the next tag, the next
            # openning code span marker, or the next escaped character.
            # Each token is then passed to handleSpanToken.
            #
			$parts = preg_split($span_re, $str, 2, PREG_SPLIT_DELIM_CAPTURE);

            # Create token from text preceding tag.
            if ($parts[0] != "") {
                $output .= $parts[0];
            }

            # Check if we reach the end.
            if (isset($parts[1])) {
                $output .= $this->handleSpanToken($parts[1], $parts[2]);
                $str = $parts[2];
            } else {
                break;
            }
        }

        return $output;
    }

    protected function handleSpanToken($token, &$str) {
        #
        # Handle $token provided by parseSpan by determining its nature and
        # returning the corresponding value that should replace it.
        #
		switch ($token{0}) {
            case "\\":
                return $this->hashPart("&#" . ord($token{1}) . ";");
            case "`":
                # Search for end marker in remaining text.
                if (preg_match('/^(.*?[^`])' . preg_quote($token) . '(?!`)(.*)$/sm', $str, $matches)) {
                    $str = $matches[2];
                    $codespan = $this->makeCodeSpan($matches[1]);
                    return $this->hashPart($codespan);
                }
                return $token; // return as text since no ending marker found.
            default:
                return $this->hashPart($token);
        }
    }

    protected function outdent($text) {
        #
        # Remove one level of line-leading tabs or spaces
        #
		return preg_replace('/^(\t|[ ]{1,' . $this->tab_width . '})/m', '', $text);
    }

    protected function detab($text) {
        #
        # Replace tabs with the appropriate amount of space.
        #
		# For each line we separate the line in blocks delemited by
        # tab characters. Then we reconstruct every line by adding the
        # appropriate number of space between each blocks.

        $text = preg_replace_callback('/^.*\t.*$/m', array($this, '_detab_callback'), $text);

        return $text;
    }

    protected function _detab_callback($matches) {
        $line = $matches[0];
        $strlen = $this->utf8_strlen; # strlen protected function for UTF-8.
        # Split in blocks.
        $blocks = explode("\t", $line);
        # Add each blocks to the line.
        $line = $blocks[0];
        unset($blocks[0]); # Do not add first block twice.
        foreach ($blocks as $block) {
            # Calculate amount of space, insert spaces, insert block.
            $amount = $this->tab_width -
                    $strlen($line, 'UTF-8') % $this->tab_width;
            $line .= str_repeat(" ", $amount) . $block;
        }

        return $line;
    }

    protected function _initDetab() {
        #
        # Check for the availability of the protected function in the `utf8_strlen` property
        # (initially `mb_strlen`). If the protected function is not available, create a
        # protected function that will loosely count the number of UTF-8 characters with a
        # regular expression.
        #
		if (function_exists($this->utf8_strlen))
            return;
        $this->utf8_strlen = create_function('$text', 'return preg_match_all(
			"/[\\\\x00-\\\\xBF]|[\\\\xC0-\\\\xFF][\\\\x80-\\\\xBF]*/", 
			$text, $m);');
    }

    protected function unhash($text) {
        #
        # Swap back in all the tags hashed by _HashHTMLBlocks.
        #
		return preg_replace_callback('/(.)\x1A[0-9]+\1/', array($this, '_unhash_callback'), $text);
    }

    protected function _unhash_callback($matches) {
        return $this->html_hashes[$matches[0]];
    }

}

#
# Markdown Extra Parser Class
#

class Markdown extends Markdownbase {
    # Prefix for footnote ids.

    protected $fn_id_prefix = "";

    # Optional title attribute for footnote links and backlinks.
    protected $fn_link_title = self::MARKDOWN_FN_LINK_TITLE;
    protected $fn_backlink_title = self::MARKDOWN_FN_BACKLINK_TITLE;

    # Optional class attribute for footnote links and backlinks.
    protected $fn_link_class = self::MARKDOWN_FN_LINK_CLASS;
    protected $fn_backlink_class = self::MARKDOWN_FN_BACKLINK_CLASS;

    # Predefined abbreviations.
    protected $predef_abbr = array();

    ### HTML Block Parser ###
    # Tags that are always treated as block tags:
    protected $block_tags_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|form|fieldset|iframe|hr|legend';

    # Tags treated as block tags only if the opening tag is alone on it's line:
    protected $context_block_tags_re = 'script|noscript|math|ins|del';

    # Tags where markdown="1" default to span mode:
    protected $contain_span_tags_re = 'p|h[1-6]|li|dd|dt|td|th|legend|address';

    # Tags which must not have their contents modified, no matter where
    # they appear:
    protected $clean_tags_re = 'script|math';

    # Tags that do not need to be closed.
    protected $auto_close_tags_re = 'hr|img';

    # Extra variables used during extra transformations.
    protected $footnotes = array();
    protected $footnotes_ordered = array();
    protected $abbr_desciptions = array();
    protected $abbr_word_re = '';

    # Give the current footnote number.
    protected $footnote_counter = 1;


    #
    # Redefining emphasis markers so that emphasis by underscore does not
    # work in the middle of a word.
    #
	protected $em_relist = array(
        '' => '(?:(?<!\*)\*(?!\*)|(?<![a-zA-Z0-9_])_(?!_))(?=\S|$)(?![.,:;]\s)',
        '*' => '(?<=\S|^)(?<!\*)\*(?!\*)',
        '_' => '(?<=\S|^)(?<!_)_(?![a-zA-Z0-9_])',
    );
    protected $strong_relist = array(
        '' => '(?:(?<!\*)\*\*(?!\*)|(?<![a-zA-Z0-9_])__(?!_))(?=\S|$)(?![.,:;]\s)',
        '**' => '(?<=\S|^)(?<!\*)\*\*(?!\*)',
        '__' => '(?<=\S|^)(?<!_)__(?![a-zA-Z0-9_])',
    );
    protected $em_strong_relist = array(
        '' => '(?:(?<!\*)\*\*\*(?!\*)|(?<![a-zA-Z0-9_])___(?!_))(?=\S|$)(?![.,:;]\s)',
        '***' => '(?<=\S|^)(?<!\*)\*\*\*(?!\*)',
        '___' => '(?<=\S|^)(?<!_)___(?![a-zA-Z0-9_])',
    );

    public function __construct() {
        #
        # Constructor function. Initialize the parser object.
        #
		# Add extra escapable characters before parent constructor
        # initialize the table.
        $this->escape_chars .= ':|';

        # Insert extra document, block, and span transformations.
        # Parent constructor will do the sorting.
        $this->document_gamut += array(
            "doFencedCodeBlocks" => 5,
            "stripFootnotes" => 15,
            "stripAbbreviations" => 25,
            "appendFootnotes" => 50,
        );

        $this->block_gamut += array(
            "doFencedCodeBlocks" => 5,
            "doTables" => 15,
            "doDefLists" => 45,
        );

        $this->span_gamut += array(
            "doFootnotes" => 5,
            "doAbbreviations" => 70,
        );

        parent::__construct();
    }

    public static function factory() {
        return new self();
    }

    public static function parse($string) {
        $o = new self();

        return $o->transform($string);
    }

    protected function setup() {
        #
        # Setting up Extra-specific variables.
        #
		parent::setup();

        $this->footnotes = array();
        $this->footnotes_ordered = array();
        $this->abbr_desciptions = array();
        $this->abbr_word_re = '';
        $this->footnote_counter = 1;

        foreach ($this->predef_abbr as $abbr_word => $abbr_desc) {
            if ($this->abbr_word_re)
                $this->abbr_word_re .= '|';
            $this->abbr_word_re .= preg_quote($abbr_word);
            $this->abbr_desciptions[$abbr_word] = trim($abbr_desc);
        }
    }

    protected function teardown() {
        #
        # Clearing Extra-specific variables.
        #
		$this->footnotes = array();
        $this->footnotes_ordered = array();
        $this->abbr_desciptions = array();
        $this->abbr_word_re = '';

        parent::teardown();
    }

    protected function hashHTMLBlocks($text) {
        #
        # Hashify HTML Blocks and "clean tags".
        #
		# We only want to do this for block-level HTML tags, such as headers,
        # lists, and tables. That's because we still want to wrap <p>s around
        # "paragraphs" that are wrapped in non-block-level tags, such as anchors,
        # phrase emphasis, and spans. The list of tags we're looking for is
        # hard-coded.
        #
		# This works by calling _HashHTMLBlocks_InMarkdown, which then calls
        # _HashHTMLBlocks_InHTML when it encounter block tags. When the markdown="1"
        # attribute is found whitin a tag, _HashHTMLBlocks_InHTML calls back
        #  _HashHTMLBlocks_InMarkdown to handle the Markdown syntax within the tag.
        # These two functions are calling each other. It's recursive!
        #
		#
		# Call the HTML-in-Markdown hasher.
        #
		list($text, ) = $this->_hashHTMLBlocks_inMarkdown($text);

        return $text;
    }

    /**
     *
     * Parse markdown text, calling _HashHTMLBlocks_InHTML for block tags.
     *
     * *   $indent is the number of space to be ignored when checking for code
     *     blocks. This is important because if we don't take the indent into
     *     account, something like this (which looks right) won't work as expected:
     *
     *     <div>
     *         <div markdown="1">
     *         Hello World.  <-- Is this a Markdown code block or text?
     *         </div>  <-- Is this a Markdown code block or a real tag?
     *     <div>
     *
     *     If you don't like this, just don't indent the tag on which
     *     you apply the markdown="1" attribute.
     *
     * *   If $enclosing_tag_re is not empty, stops at the first unmatched closing
     *     tag with that name. Nested tags supported.
     *
     * *   If $span is true, text inside must treated as span. So any double
     *     newline will be replaced by a single newline so that it does not create
     *     paragraphs.
     *
     * Returns an array of that form: ( processed text , remaining text )
     *
     */
    protected function _hashHTMLBlocks_inMarkdown($text, $indent = 0, $enclosing_tag_re = '', $span = false) {

        if ($text === '')
            return array('', '');

        # Regex to check for the presense of newlines around a block tag.
        $newline_before_re = '/(?:^\n?|\n\n)*$/';
        $newline_after_re =
                '{
				^						# Start of text following the tag.
				(?>[ ]*<!--.*?-->)?		# Optional comment.
				[ ]*\n					# Must be followed by newline.
			}xs';

        # Regex to match any tag.
        $block_tag_re =
                '{
				(					# $2: Capture hole tag.
					</?					# Any opening or closing tag.
						(?>				# Tag name.
							' . $this->block_tags_re . '			|
							' . $this->context_block_tags_re . '	|
							' . $this->clean_tags_re . '        	|
							(?!\s)' . $enclosing_tag_re . '
						)
						(?:
							(?=[\s"\'/a-zA-Z0-9])	# Allowed characters after tag name.
							(?>
								".*?"		|	# Double quotes (can contain `>`)
								\'.*?\'   	|	# Single quotes (can contain `>`)
								.+?				# Anything but quotes and `>`.
							)*?
						)?
					>					# End of tag.
				|
					<!--    .*?     -->	# HTML Comment
				|
					<\?.*?\?> | <%.*?%>	# Processing instruction
				|
					<!\[CDATA\[.*?\]\]>	# CData Block
				|
					# Code span marker
					`+
				' . (!$span ? ' # If not in span.
				|
					# Indented code block
					(?: ^[ ]*\n | ^ | \n[ ]*\n )
					[ ]{' . ($indent + 4) . '}[^\n]* \n
					(?>
						(?: [ ]{' . ($indent + 4) . '}[^\n]* | [ ]* ) \n
					)*
				|
					# Fenced code block marker
					(?> ^ | \n )
					[ ]{' . ($indent) . '}~~~+[ ]*\n
				' : '' ) . ' # End (if not is span).
				)
			}xs';


        $depth = 0;  # Current depth inside the tag tree.
        $parsed = ""; # Parsed text that will be returned.
        #
		# Loop through every tag until we find the closing tag of the parent
        # or loop until reaching the end of text if no parent tag specified.
        #
		do {
            #
            # Split the text using the first $tag_match pattern found.
            # Text before  pattern will be first in the array, text after
            # pattern will be at the end, and between will be any catches made
            # by the pattern.
            #
			$parts = preg_split($block_tag_re, $text, 2, PREG_SPLIT_DELIM_CAPTURE);

            # If in Markdown span mode, add a empty-string span-level hash
            # after each newline to prevent triggering any block element.
            if ($span) {
                $void = $this->hashPart("", ':');
                $newline = "$void\n";
                $parts[0] = $void . str_replace("\n", $newline, $parts[0]) . $void;
            }

            $parsed .= $parts[0]; # Text before current tag.
            # If end of $text has been reached. Stop loop.
            if (count($parts) < 3) {
                $text = "";
                break;
            }

            $tag = $parts[1]; # Tag to handle.
            $text = $parts[2]; # Remaining text after current tag.
            $tag_re = preg_quote($tag); # For use in a regular expression.
            #
			# Check for: Code span marker
            #
			if ($tag{0} == "`") {
                # Find corresponding end marker.
                $tag_re = preg_quote($tag);
                if (preg_match('{^(?>.+?|\n(?!\n))*?(?<!`)' . $tag_re . '(?!`)}', $text, $matches)) {
                    # End marker found: pass text unchanged until marker.
                    $parsed .= $tag . $matches[0];
                    $text = substr($text, strlen($matches[0]));
                } else {
                    # Unmatched marker: just skip it.
                    $parsed .= $tag;
                }
            }
            #
            # Check for: Indented code block.
            #
			else if ($tag{0} == "\n" || $tag{0} == " ") {
                # Indented code block: pass it unchanged, will be handled
                # later.
                $parsed .= $tag;
            }
            #
            # Check for: Fenced code block marker.
            #
			else if ($tag{0} == "~") {
                # Fenced code block marker: find matching end marker.
                $tag_re = preg_quote(trim($tag));
                if (preg_match('{^(?>.*\n)+?' . $tag_re . ' *\n}', $text, $matches)) {
                    # End marker found: pass text unchanged until marker.
                    $parsed .= $tag . $matches[0];
                    $text = substr($text, strlen($matches[0]));
                } else {
                    # No end marker: just skip it.
                    $parsed .= $tag;
                }
            }
            #
            # Check for: Opening Block level tag or
            #            Opening Context Block tag (like ins and del)
            #               used as a block tag (tag is alone on it's line).
            #
			else if (preg_match('{^<(?:' . $this->block_tags_re . ')\b}', $tag) ||
                    ( preg_match('{^<(?:' . $this->context_block_tags_re . ')\b}', $tag) &&
                    preg_match($newline_before_re, $parsed) &&
                    preg_match($newline_after_re, $text) )
            ) {
                # Need to parse tag and following text using the HTML parser.
                list($block_text, $text) =
                        $this->_hashHTMLBlocks_inHTML($tag . $text, "hashBlock", true);

                # Make sure it stays outside of any paragraph by adding newlines.
                $parsed .= "\n\n$block_text\n\n";
            }
            #
            # Check for: Clean tag (like script, math)
            #            HTML Comments, processing instructions.
            #
			else if (preg_match('{^<(?:' . $this->clean_tags_re . ')\b}', $tag) ||
                    $tag{1} == '!' || $tag{1} == '?') {
                # Need to parse tag and following text using the HTML parser.
                # (don't check for markdown attribute)
                list($block_text, $text) =
                        $this->_hashHTMLBlocks_inHTML($tag . $text, "hashClean", false);

                $parsed .= $block_text;
            }
            #
            # Check for: Tag with same name as enclosing tag.
            #
			else if ($enclosing_tag_re !== '' &&
                    # Same name as enclosing tag.
                    preg_match('{^</?(?:' . $enclosing_tag_re . ')\b}', $tag)) {
                #
                # Increase/decrease nested tag count.
                #
				if ($tag{1} == '/')
                    $depth--;
                else if ($tag{strlen($tag) - 2} != '/')
                    $depth++;

                if ($depth < 0) {
                    #
                    # Going out of parent element. Clean up and break so we
                    # return to the calling function.
                    #
					$text = $tag . $text;
                    break;
                }

                $parsed .= $tag;
            } else {
                $parsed .= $tag;
            }
        } while ($depth >= 0);

        return array($parsed, $text);
    }

    protected function _hashHTMLBlocks_inHTML($text, $hash_method, $md_attr) {
        #
        # Parse HTML, calling _HashHTMLBlocks_InMarkdown for block tags.
        #
		# *   Calls $hash_method to convert any blocks.
        # *   Stops when the first opening tag closes.
        # *   $md_attr indicate if the use of the `markdown="1"` attribute is allowed.
        #     (it is not inside clean tags)
        #
		# Returns an array of that form: ( processed text , remaining text )
        #
		if ($text === '')
            return array('', '');

        // Regex to match `markdown` attribute inside of a tag.
        $markdown_attr_re = '
			{
				\s*			# Eat whitespace before the `markdown` attribute
				markdown
				\s*=\s*
				(?>
					(["\'])		# $1: quote delimiter		
					(.*?)		# $2: attribute value
					\1			# matching delimiter	
				|
					([^\s>]*)	# $3: unquoted attribute value
				)
				()				# $4: make $3 always defined (avoid warnings)
			}xs';

        // Regex to match any tag.
        $tag_re = '{
				(					# $2: Capture hole tag.
					</?					# Any opening or closing tag.
						[\w:$]+			# Tag name.
						(?:
							(?=[\s"\'/a-zA-Z0-9])	# Allowed characters after tag name.
							(?>
								".*?"		|	# Double quotes (can contain `>`)
								\'.*?\'   	|	# Single quotes (can contain `>`)
								.+?				# Anything but quotes and `>`.
							)*?
						)?
					>					# End of tag.
				|
					<!--    .*?     -->	# HTML Comment
				|
					<\?.*?\?> | <%.*?%>	# Processing instruction
				|
					<!\[CDATA\[.*?\]\]>	# CData Block
				)
			}xs';

        $original_text = $text;  # Save original text in case of faliure.

        $depth = 0; # Current depth inside the tag tree.
        $block_text = ""; # Temporary text holder for current text.
        $parsed = ""; # Parsed text that will be returned.
        #
		# Get the name of the starting tag.
        # (This pattern makes $base_tag_name_re safe without quoting.)
        #
		if (preg_match('/^<([\w:$]*)\b/', $text, $matches))
            $base_tag_name_re = $matches[1];

        #
        # Loop through every tag until we find the corresponding closing tag.
        #
		do {
            /**
              # Split the text using the first $tag_match pattern found.
              # Text before  pattern will be first in the array, text after
              # pattern will be at the end, and between will be any catches made
              # by the pattern.
              # */
            $parts = preg_split($tag_re, $text, 2, PREG_SPLIT_DELIM_CAPTURE);

            if (count($parts) < 3) {
                /**
                 * End of $text reached with unbalenced tag(s).
                 * In that case, we return original text unchanged and pass the
                 * first character as filtered to prevent an infinite loop in the
                 * parent function.
                 */
                return array($original_text{0}, substr($original_text, 1));
            }

            $block_text .= $parts[0]; # Text before current tag.
            $tag = $parts[1]; # Tag to handle.
            $text = $parts[2]; # Remaining text after current tag.
            #
			# Check for: Auto-close tag (like <hr/>)
            #			 Comments and Processing Instructions.
            #
			if (preg_match('{^</?(?:' . $this->auto_close_tags_re . ')\b}', $tag) ||
                    $tag{1} == '!' || $tag{1} == '?') {
                # Just add the tag to the block as if it was text.
                $block_text .= $tag;
            } else {
                #
                # Increase/decrease nested tag count. Only do so if
                # the tag's name match base tag's.
                #
				if (preg_match('{^</?' . $base_tag_name_re . '\b}', $tag)) {
                    if ($tag{1} == '/')
                        $depth--;
                    else if ($tag{strlen($tag) - 2} != '/')
                        $depth++;
                }

                #
                # Check for `markdown="1"` attribute and handle it.
                #
				if ($md_attr &&
                        preg_match($markdown_attr_re, $tag, $attr_m) &&
                        preg_match('/^1|block|span$/', $attr_m[2] . $attr_m[3])) {
                    # Remove `markdown` attribute from opening tag.
                    $tag = preg_replace($markdown_attr_re, '', $tag);

                    # Check if text inside this tag must be parsed in span mode.
                    $this->mode = $attr_m[2] . $attr_m[3];
                    $span_mode = $this->mode == 'span' || $this->mode != 'block' &&
                            preg_match('{^<(?:' . $this->contain_span_tags_re . ')\b}', $tag);

                    # Calculate indent before tag.
                    if (preg_match('/(?:^|\n)( *?)(?! ).*?$/', $block_text, $matches)) {
                        $strlen = $this->utf8_strlen;
                        $indent = $strlen($matches[1], 'UTF-8');
                    } else {
                        $indent = 0;
                    }

                    # End preceding block with this tag.
                    $block_text .= $tag;
                    $parsed .= $this->$hash_method($block_text);

                    # Get enclosing tag name for the ParseMarkdown function.
                    # (This pattern makes $tag_name_re safe without quoting.)
                    preg_match('/^<([\w:$]*)\b/', $tag, $matches);
                    $tag_name_re = $matches[1];

                    # Parse the content using the HTML-in-Markdown parser.
                    list ($block_text, $text)
                            = $this->_hashHTMLBlocks_inMarkdown($text, $indent, $tag_name_re, $span_mode);

                    # Outdent markdown text.
                    if ($indent > 0) {
                        $block_text = preg_replace("/^[ ]{1,$indent}/m", "", $block_text);
                    }

                    # Append tag content to parsed text.
                    if (!$span_mode)
                        $parsed .= "\n\n$block_text\n\n";
                    else
                        $parsed .= "$block_text";

                    # Start over a new block.
                    $block_text = "";
                }
                else
                    $block_text .= $tag;
            }
        } while ($depth > 0);


        // Hash last block text that wasn't processed inside the loop.
        $parsed .= $this->$hash_method($block_text);

        return array($parsed, $text);
    }

    /**
     * Called whenever a tag must be hashed when a protected function insert a "clean" tag
     * in $text, it pass through this protected function and is automaticaly escaped,
     * blocking invalid nested overlap.
     */
    protected function hashClean($text) {

        return $this->hashPart($text, 'C');
    }

    protected function doHeaders($text) {
        #
        # Redefined to add id attribute support.
        #
		# Setext-style headers:
        #	  Header 1  {#header1}
        #	  ========
        #
		#	  Header 2  {#header2}
        #	  --------
        #
		$text = preg_replace_callback(
                '{
				(^.+?)								# $1: Header text
				(?:[ ]+\{\#([-_:a-zA-Z0-9]+)\})?	# $2: Id attribute
				[ ]*\n(=+|-+)[ ]*\n+				# $3: Header footer
			}mx', array($this, '_doHeaders_callback_setext'), $text);

        /**
         * 	atx-style headers:
         * 	# Header 1        {#header1}
         * 	## Header 2       {#header2}
         * 	## Header 2 with closing hashes ##  {#header3}
         * 	...
         * 	###### Header 6   {#header2}
         *
         */
        $text = preg_replace_callback('{
				^(\#{1,6})	# $1 = string of #\'s
				[ ]*
				(.+?)		# $2 = Header text
				[ ]*
				\#*			# optional closing #\'s (not counted)
				(?:[ ]+\{\#([-_:a-zA-Z0-9]+)\})? # id attribute
				[ ]*
				\n+
			}xm', array($this, '_doHeaders_callback_atx'), $text);

        return $text;
    }

    protected function _doHeaders_attr($attr) {
        if (empty($attr))
            return "";

        return " id=\"$attr\"";
    }

    protected function _doHeaders_callback_setext($matches) {
        if ($matches[3] == '-' && preg_match('{^- }', $matches[1])) {
            return $matches[0];
        }

        $level = $matches[3]{0} == '=' ? 1 : 2;
        $attr = $this->_doHeaders_attr($id = & $matches[2]);
        $block = "<h$level$attr>" . $this->runSpanGamut($matches[1]) . "</h$level>";

        return "\n" . $this->hashBlock($block) . "\n\n";
    }

    protected function _doHeaders_callback_atx($matches) {
        $level = strlen($matches[1]);
        $attr = $this->_doHeaders_attr($id = & $matches[3]);
        $block = "<h$level$attr>" . $this->runSpanGamut($matches[2]) . "</h$level>";

        return "\n" . $this->hashBlock($block) . "\n\n";
    }

    protected function doTables($text) {
        #
        # Form HTML tables.
        #
		$less_than_tab = $this->tab_width - 1;
        #
        # Find tables with leading pipe.
        #
		#	| Header 1 | Header 2
        #	| -------- | --------
        #	| Cell 1   | Cell 2
        #	| Cell 3   | Cell 4
        #
		$text = preg_replace_callback('
			{
				^							# Start of a line
				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
				[|]							# Optional leading pipe (present)
				(.+) \n						# $1: Header row (at least one pipe)
				
				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
				[|] ([ ]*[-:]+[-| :]*) \n	# $2: Header underline
				
				(							# $3: Cells
					(?>
						[ ]*				# Allowed whitespace.
						[|] .* \n			# Row content.
					)*
				)
				(?=\n|\Z)					# Stop at final double newline.
			}xm', array($this, '_doTable_leadingPipe_callback'), $text);

        #
        # Find tables without leading pipe.
        #
		#	Header 1 | Header 2
        #	-------- | --------
        #	Cell 1   | Cell 2
        #	Cell 3   | Cell 4
        #
		$text = preg_replace_callback('
			{
				^							# Start of a line
				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
				(\S.*[|].*) \n				# $1: Header row (at least one pipe)
				
				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
				([-:]+[ ]*[|][-| :]*) \n	# $2: Header underline
				
				(							# $3: Cells
					(?>
						.* [|] .* \n		# Row content
					)*
				)
				(?=\n|\Z)					# Stop at final double newline.
			}xm', array($this, '_DoTable_callback'), $text);

        return $text;
    }

    protected function _doTable_leadingPipe_callback($matches) {
        $head = $matches[1];
        $underline = $matches[2];
        $content = $matches[3];

        # Remove leading pipe for each row.
        $content = preg_replace('/^ *[|]/m', '', $content);

        return $this->_doTable_callback(array($matches[0], $head, $underline, $content));
    }

    protected function _doTable_callback($matches) {
        $head = $matches[1];
        $underline = $matches[2];
        $content = $matches[3];

        # Remove any tailing pipes for each line.
        $head = preg_replace('/[|] *$/m', '', $head);
        $underline = preg_replace('/[|] *$/m', '', $underline);
        $content = preg_replace('/[|] *$/m', '', $content);

        # Reading alignement from header underline.
        $separators = preg_split('/ *[|] */', $underline);

        foreach ($separators as $n => $s) {
            if (preg_match('/^ *-+: *$/', $s))
                $attr[$n] = ' align="right"';
            else if (preg_match('/^ *:-+: *$/', $s))
                $attr[$n] = ' align="center"';
            else if (preg_match('/^ *:-+ *$/', $s))
                $attr[$n] = ' align="left"';
            else
                $attr[$n] = '';
        }

        # Parsing span elements, including code spans, character escapes,
        # and inline HTML tags, so that pipes inside those gets ignored.
        $head = $this->parseSpan($head);
        $headers = preg_split('/ *[|] */', $head);
        $col_count = count($headers);

        # Write column headers.
        $text = "<table>\n";
        $text .= "<thead>\n";
        $text .= "<tr>\n";

        foreach ($headers as $n => $header)
            $text .= "  <th$attr[$n]>" . $this->runSpanGamut(trim($header)) . "</th>\n";
        $text .= "</tr>\n";
        $text .= "</thead>\n";

        # Split content by row.
        $rows = explode("\n", trim($content, "\n"));

        $text .= "<tbody>\n";
        foreach ($rows as $row) {
            # Parsing span elements, including code spans, character escapes,
            # and inline HTML tags, so that pipes inside those gets ignored.
            $row = $this->parseSpan($row);

            # Split row by cell.
            $row_cells = preg_split('/ *[|] */', $row, $col_count);
            $row_cells = array_pad($row_cells, $col_count, '');

            $text .= "<tr>\n";
            foreach ($row_cells as $n => $cell)
                $text .= "  <td$attr[$n]>" . $this->runSpanGamut(trim($cell)) . "</td>\n";
            $text .= "</tr>\n";
        }
        $text .= "</tbody>\n";
        $text .= "</table>";

        return $this->hashBlock($text) . "\n";
    }

    protected function doDefLists($text) {
        #
        # Form HTML definition lists.
        #
		$less_than_tab = $this->tab_width - 1;

        # Re-usable pattern to match any entire dl list:
        $whole_list_re = '(?>
			(								# $1 = whole list
			  (								# $2
				[ ]{0,' . $less_than_tab . '}
				((?>.*\S.*\n)+)				# $3 = defined term
				\n?
				[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
			  )
			  (?s:.+?)
			  (								# $4
				  \z
				|
				  \n{2,}
				  (?=\S)
				  (?!						# Negative lookahead for another term
					[ ]{0,' . $less_than_tab . '}
					(?: \S.*\n )+?			# defined term
					\n?
					[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
				  )
				  (?!						# Negative lookahead for another definition
					[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
				  )
			  )
			)
		)'; // mx

        $text = preg_replace_callback('{
				(?>\A\n?|(?<=\n\n))
				' . $whole_list_re . '
			}mx', array($this, '_doDefLists_callback'), $text);

        return $text;
    }

    protected function _doDefLists_callback($matches) {
        # Re-usable patterns to match list item bullets and number markers:
        $list = $matches[1];

        # Turn double returns into triple returns, so that we can make a
        # paragraph for the last item in a list, if necessary:
        $result = trim($this->processDefListItems($list));
        $result = "<dl>\n" . $result . "\n</dl>";
        return $this->hashBlock($result) . "\n\n";
    }

    protected function processDefListItems($list_str) {
        #
        #	Process the contents of a single definition list, splitting it
        #	into individual term and definition list items.
        #
		$less_than_tab = $this->tab_width - 1;

        # trim trailing blank lines:
        $list_str = preg_replace("/\n{2,}\\z/", "\n", $list_str);

        # Process definition terms.
        $list_str = preg_replace_callback('{
			(?>\A\n?|\n\n+)					# leading line
			(								# definition terms = $1
				[ ]{0,' . $less_than_tab . '}	# leading whitespace
				(?![:][ ]|[ ])				# negative lookahead for a definition 
											#   mark (colon) or more whitespace.
				(?> \S.* \n)+?				# actual term (not whitespace).	
			)			
			(?=\n?[ ]{0,3}:[ ])				# lookahead for following line feed 
											#   with a definition mark.
			}xm', array($this, '_processDefListItems_callback_dt'), $list_str);

        # Process actual definitions.
        $list_str = preg_replace_callback('{
			\n(\n+)?						# leading line = $1
			(								# marker space = $2
				[ ]{0,' . $less_than_tab . '}	# whitespace before colon
				[:][ ]+						# definition mark (colon)
			)
			((?s:.+?))						# definition text = $3
			(?= \n+ 						# stop at next definition mark,
				(?:							# next term or end of text
					[ ]{0,' . $less_than_tab . '} [:][ ]	|
					<dt> | \z
				)						
			)					
			}xm', array($this, '_processDefListItems_callback_dd'), $list_str);

        return $list_str;
    }

    protected function _processDefListItems_callback_dt($matches) {
        $terms = explode("\n", trim($matches[1]));
        $text = '';
        foreach ($terms as $term) {
            $term = $this->runSpanGamut(trim($term));
            $text .= "\n<dt>" . $term . "</dt>";
        }

        return $text . "\n";
    }

    protected function _processDefListItems_callback_dd($matches) {
        $leading_line = $matches[1];
        $marker_space = $matches[2];
        $def = $matches[3];

        if ($leading_line || preg_match('/\n{2,}/', $def)) {
            # Replace marker with the appropriate whitespace indentation
            $def = str_repeat(' ', strlen($marker_space)) . $def;
            $def = $this->runBlockGamut($this->outdent($def . "\n\n"));
            $def = "\n" . $def . "\n";
        } else {
            $def = rtrim($def);
            $def = $this->runSpanGamut($this->outdent($def));
        }

        return "\n<dd>" . $def . "</dd>\n";
    }

    /**
     * Adding the fenced code block syntax to regular Markdown:
     *  ~~~
     *  Code block
     *  ~~~
     *
     * @param string $text
     */
    protected function doFencedCodeBlocks($text) {

        $less_than_tab = $this->tab_width;

        $text = preg_replace_callback('{
				(?:\n|\A)
				# 1: Opening marker
				(
					~{3,} # Marker: three tilde or more.
				)
				[ ]* \n # Whitespace and newline following marker.
				
				# 2: Content
				(
					(?>
						(?!\1 [ ]* \n)	# Not a closing marker.
						.*\n+
					)+
				)
				
				# Closing marker.
				\1 [ ]* \n
			}xm', array($this, '_doFencedCodeBlocks_callback'), $text);

        return $text;
    }

    protected function _doFencedCodeBlocks_callback($matches) {
        $codeblock = $matches[2];
        $codeblock = htmlspecialchars($codeblock, ENT_NOQUOTES);
        $codeblock = preg_replace_callback('/^\n+/', array($this, '_doFencedCodeBlocks_newlines'), $codeblock);

        $codeblock = "<pre><code>$codeblock</code></pre>";

        return "\n\n" . $this->hashBlock($codeblock) . "\n\n";
    }

    protected function _doFencedCodeBlocks_newlines($matches) {
        return str_repeat("<br$this->empty_element_suffix", strlen($matches[0]));
    }

    protected function formParagraphs($text) {
        #
        #	Params:
        #		$text - string to process with html <p> tags
        #
		# Strip leading and trailing lines:
        $text = preg_replace('/\A\n+|\n+\z/', '', $text);

        $grafs = preg_split('/\n{2,}/', $text, -1, PREG_SPLIT_NO_EMPTY);


        // Wrap <p> tags and unhashify HTML blocks
        foreach ($grafs as $key => $value) {
            $value = trim($this->runSpanGamut($value));

            # Check if this should be enclosed in a paragraph.
            # Clean tag hashes & block tag hashes are left alone.
            $is_p = !preg_match('/^B\x1A[0-9]+B|^C\x1A[0-9]+C$/', $value);

            if ($is_p) {
                $value = "<p>$value</p>";
            }
            $grafs[$key] = $value;
        }

        // Join grafs in one text, then unhash HTML tags.
        $text = implode("\n\n", $grafs);

        // Finish by removing any tag hashes still present in $text.
        $text = $this->unhash($text);

        return $text;
    }

    protected function stripFootnotes($text) {
        #
        # Strips link definitions from text, stores the URLs and titles in
        # hash references.
        #
		$less_than_tab = $this->tab_width - 1;

        # Link defs are in the form: [^id]: url "optional title"
        $text = preg_replace_callback('{
			^[ ]{0,' . $less_than_tab . '}\[\^(.+?)\][ ]?:	# note_id = $1
			  [ ]*
			  \n?					# maybe *one* newline
			(						# text = $2 (no blank lines allowed)
				(?:					
					.+				# actual text
				|
					\n				# newlines but 
					(?!\[\^.+?\]:\s)# negative lookahead for footnote marker.
					(?!\n+[ ]{0,3}\S)# ensure line is not blank and followed 
									# by non-indented content
				)*
			)		
			}xm', array($this, '_stripFootnotes_callback'), $text);

        return $text;
    }

    protected function _stripFootnotes_callback($matches) {
        $note_id = $this->fn_id_prefix . $matches[1];
        $this->footnotes[$note_id] = $this->outdent($matches[2]);
        return ''; # String that will replace the block
    }

    protected function doFootnotes($text) {
        #
        # Replace footnote references in $text [^id] with a special text-token
        # which will be replaced by the actual footnote marker in appendFootnotes.
        #
		if (!$this->in_anchor) {
            $text = preg_replace('{\[\^(.+?)\]}', "F\x1Afn:\\1\x1A:", $text);
        }

        return $text;
    }

    protected function appendFootnotes($text) {
        #
        # Append footnote list to text.
        #
		$text = preg_replace_callback('{F\x1Afn:(.*?)\x1A:}', array($this, '_appendFootnotes_callback'), $text);

        if (!empty($this->footnotes_ordered)) {
            $text .= "\n\n";
            $text .= "<div class=\"footnotes\">\n";
            $text .= "<hr" . $this->empty_element_suffix . "\n";
            $text .= "<ol>\n\n";

            $attr = " rev=\"footnote\"";
            if ($this->fn_backlink_class != "") {
                $class = $this->fn_backlink_class;
                $class = $this->encodeAttribute($class);
                $attr .= " class=\"$class\"";
            }
            if ($this->fn_backlink_title != "") {
                $title = $this->fn_backlink_title;
                $title = $this->encodeAttribute($title);
                $attr .= " title=\"$title\"";
            }
            $num = 0;

            while (!empty($this->footnotes_ordered)) {
                $footnote = reset($this->footnotes_ordered);
                $note_id = key($this->footnotes_ordered);
                unset($this->footnotes_ordered[$note_id]);

                $footnote .= "\n"; # Need to append newline before parsing.
                $footnote = $this->runBlockGamut("$footnote\n");
                $footnote = preg_replace_callback('{F\x1Afn:(.*?)\x1A:}', array($this, '_appendFootnotes_callback'), $footnote);

                $attr = str_replace("%%", ++$num, $attr);
                $note_id = $this->encodeAttribute($note_id);

                # Add backlink to last paragraph; create new paragraph if needed.
                $backlink = "<a href=\"#fnref:$note_id\"$attr>&#8617;</a>";
                if (preg_match('{</p>$}', $footnote)) {
                    $footnote = substr($footnote, 0, -4) . "&#160;$backlink</p>";
                } else {
                    $footnote .= "\n\n<p>$backlink</p>";
                }

                $text .= "<li id=\"fn:$note_id\">\n";
                $text .= $footnote . "\n";
                $text .= "</li>\n\n";
            }

            $text .= "</ol>\n";
            $text .= "</div>";
        }

        return $text;
    }

    protected function _appendFootnotes_callback($matches) {
        $node_id = $this->fn_id_prefix . $matches[1];

        # Create footnote marker only if it has a corresponding footnote *and*
        # the footnote hasn't been used by another marker.
        if (isset($this->footnotes[$node_id])) {
            # Transfert footnote content to the ordered list.
            $this->footnotes_ordered[$node_id] = $this->footnotes[$node_id];
            unset($this->footnotes[$node_id]);

            $num = $this->footnote_counter++;
            $attr = " rel=\"footnote\"";
            if ($this->fn_link_class != "") {
                $class = $this->fn_link_class;
                $class = $this->encodeAttribute($class);
                $attr .= " class=\"$class\"";
            }
            if ($this->fn_link_title != "") {
                $title = $this->fn_link_title;
                $title = $this->encodeAttribute($title);
                $attr .= " title=\"$title\"";
            }

            $attr = str_replace("%%", $num, $attr);
            $node_id = $this->encodeAttribute($node_id);

            return
                    "<sup id=\"fnref:$node_id\">" .
                    "<a href=\"#fn:$node_id\"$attr>$num</a>" .
                    "</sup>";
        }

        return "[^" . $matches[1] . "]";
    }

    protected function stripAbbreviations($text) {
        #
        # Strips abbreviations from text, stores titles in hash references.
        #
		$less_than_tab = $this->tab_width - 1;

        # Link defs are in the form: [id]*: url "optional title"
        $text = preg_replace_callback('{
			^[ ]{0,' . $less_than_tab . '}\*\[(.+?)\][ ]?:	# abbr_id = $1
			(.*)					# text = $2 (no blank lines allowed)	
			}xm', array($this, '_stripAbbreviations_callback'), $text);

        return $text;
    }

    protected function _stripAbbreviations_callback($matches) {
        $abbr_word = $matches[1];
        $abbr_desc = $matches[2];
        if ($this->abbr_word_re)
            $this->abbr_word_re .= '|';
        $this->abbr_word_re .= preg_quote($abbr_word);
        $this->abbr_desciptions[$abbr_word] = trim($abbr_desc);

        return ''; # String that will replace the block
    }

    protected function doAbbreviations($text) {
        #
        # Find defined abbreviations in text and wrap them in <abbr> elements.
        #
		if ($this->abbr_word_re) {
            // cannot use the /x modifier because abbr_word_re may
            // contain significant spaces:
            $text = preg_replace_callback('{' .
                    '(?<![\w\x1A])' .
                    '(?:' . $this->abbr_word_re . ')' .
                    '(?![\w\x1A])' .
                    '}', array($this, '_doAbbreviations_callback'), $text);
        }

        return $text;
    }

    protected function _doAbbreviations_callback($matches) {
        $abbr = $matches[0];
        if (isset($this->abbr_desciptions[$abbr])) {
            $desc = $this->abbr_desciptions[$abbr];
            if (empty($desc)) {

                return $this->hashPart("<abbr>$abbr</abbr>");
            } else {
                $desc = $this->encodeAttribute($desc);

                return $this->hashPart("<abbr title=\"$desc\">$abbr</abbr>");
            }
        } else {

            return $matches[0];
        }
    }

}
